The present invention relates to alpha-halotetramethylcyclohexanone which is useful as a synthetic aroma, and an intermediate in organic chemistry, and a method for the preparation thereof. The present invention relates also to a (2,3,4,4-tetramethylcyclopentyl)methyl carboxylate compound which is useful as a bioactive substance such as a sex pheromone of insects and a substance related therewith. For instance, the invention relates to a method for the preparation of (2,3,4,4-tetramethylcyclopentyl)methyl acetate which is a sex hormone of Pseudococcus viburni, or general name Obscure Mealy bug (hereinafter, called as “OMB”).